Robotic manipulator force determination

ABSTRACT

Certain aspects relate to systems and techniques for detection of undesirable forces on one or more surgical robotic arms. In one aspect, there is provided a system including a robotic arm, including: two linkages, a joint, a torque sensor, and an instrument device manipulator (IDM). The system may further include a processor configured to measure a first torque value at the joint based on an output of the torque sensor and determine a second torque value at the joint based on a position of the robotic arm. The second torque value may be indicative of a gravitational component of the torque between the two linkages. The processor may be further configured to determine a force at the IDM based a difference between the first and second torque values and determine whether the robotic arm has collided with an object or misaligned based on the force at the IDM.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of U.S. application Ser. No.16/746,615, filed Jan. 17, 2020, which is a continuation of U.S.application Ser. No. 16/026,591, filed Jul. 3, 2018, which is acontinuation of U.S. application Ser. No. 15/729,569, filed Oct. 10,2017, each of which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The systems and methods disclosed herein are directed to surgicalrobotic systems, and more particularly to detecting undesirable forceson one or more robotic arms in a surgical robotic system.

BACKGROUND

Medical procedures such as endoscopy (e.g., bronchoscopy) may involvethe insertion of a medical tool into a patient's luminal network (e.g.,airways) for diagnostic and/or therapeutic purposes. Surgical roboticsystems may be used to control the insertion and/or manipulation of thesteerable instrument tool during a medical procedure. The surgicalrobotic system may comprise at least one robotic arm including aninstrument device manipulator (IDM) assembly which may be used tocontrol the positioning of the steerable instrument during the medicalprocedure.

SUMMARY

The systems, methods and devices of this disclosure each have severalinnovative aspects, no single one of which is solely responsible for thedesirable attributes disclosed herein.

In one aspect, there is provided a system comprising: a first roboticarm, comprising: at least two linkages, at least one joint connectingthe at least two linkages, at least one torque sensor configured todetect torque between the at least two linkages, and an instrumentdevice manipulator (IDM) connected to a distal end of the first roboticarm; a processor; and a memory storing computer-executable instructionsto cause the processor to: measure a first torque value at the at leastone joint based on an output of the torque sensor, determine a secondtorque value at the at least one joint based on a position of the firstrobotic arm, the second torque value indicative of a gravitationalcomponent of the torque between the at least two linkages, determine afirst force at the IDM based on a difference between the first andsecond torque values, and determine whether the first robotic arm hascollided with an object based on the first force at the IDM.

In another aspect, there is provided a non-transitory computer readablestorage medium having stored thereon instructions that, when executed,cause at least one computing device to: measure a first torque value ata joint of a first robotic arm based on an output of a torque sensor,the first robotic arm comprising: two linkages connected by the joint, atorque sensor configured to detect torque between the two linkages, andan instrument device manipulator (IDM) connected to a distal end of thefirst robotic arm; determine a second torque value at the joint based ona position of the first robotic arm, the second torque value indicativeof a gravitational component of the torque between the two linkages;determine a first force at the IDM based on a difference between thefirst and second torque values; and determine whether the first roboticarm has collided with an object based on the first force at the IDM.

In yet another aspect, there is provided a method of positioning a firstrobotic arm, comprising: measuring a first torque value at a joint of afirst robotic arm based on an output of a torque sensor, the firstrobotic arm comprising: two linkages connected by the joint, a torquesensor configured to detect torque between the two linkages, and aninstrument device manipulator (IDM) connected to a distal end of thefirst robotic arm; determining a second torque value at the joint basedon a position of the first robotic arm, the second torque valueindicative of a gravitational component of the torque between the twolinkages; determining a first force at the IDM based on a differencebetween the first and second torque values; and determining whether thefirst robotic arm has collided with an object based on the first forceat the IDM.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed aspects will hereinafter be described in conjunction withthe appended drawings, provided to illustrate and not to limit thedisclosed aspects, wherein like designations denote like elements.

FIG. 1 illustrates an embodiment of a cart-based robotic system arrangedfor diagnostic and/or therapeutic bronchoscopy procedure(s).

FIG. 2 depicts further aspects of the robotic system of FIG. 1.

FIG. 3 illustrates an embodiment of the robotic system of FIG. 1arranged for ureteroscopy.

FIG. 4 illustrates an embodiment of the robotic system of FIG. 1arranged for a vascular procedure.

FIG. 5 illustrates an embodiment of a table-based robotic systemarranged for a bronchoscopy procedure.

FIG. 6 provides an alternative view of the robotic system of FIG. 5.

FIG. 7 illustrates an example system configured to stow robotic arm(s).

FIG. 8 illustrates an embodiment of a table-based robotic systemconfigured for a ureteroscopy procedure.

FIG. 9 illustrates an embodiment of a table-based robotic systemconfigured for a laparoscopic procedure.

FIG. 10 illustrates an embodiment of the table-based robotic system ofFIGS. 5-9 with pitch or tilt adjustment.

FIG. 11 provides a detailed illustration of the interface between thetable and the column of the table-based robotic system of FIGS. 5-10.

FIG. 12 illustrates an exemplary instrument driver.

FIG. 13 illustrates an exemplary medical instrument with a pairedinstrument driver.

FIG. 14 illustrates an alternative design for an instrument driver andinstrument where the axes of the drive units are parallel to the axis ofthe elongated shaft of the instrument.

FIG. 15 depicts a block diagram illustrating a localization system thatestimates a location of one or more elements of the robotic systems ofFIGS. 1-10, such as the location of the instrument of FIGS. 13 and 14,in accordance to an example embodiment.

FIG. 16 illustrates an embodiment of a cart-based robotic system whichmay be configured to detect robotic arm collision in accordance withaspects of this disclosure.

FIG. 17 is a flowchart which illustrates an example procedure fordetermining a force applied to a robotic arm and detecting a collisionin accordance with aspects of this disclosure.

FIG. 18 illustrates a free-body diagram of a robotic arm for describingtechniques for calculating forces applied to the robotic arm inaccordance with aspects of this disclosure.

FIG. 19A is a graph illustrating an example of the forces measuredduring insertion of a medical instrument in accordance with aspects ofthis disclosure.

FIG. 19B is a graph illustrating an example of the forces measuredduring insertion of a medical instrument which may be indicative of acollision event in accordance with aspects of this disclosure.

FIG. 19C is a graph illustrating an example of the forces measuredduring insertion of a medical instrument which may be indicative of amisalignment event in accordance with aspects of this disclosure.

FIG. 20 is a flowchart illustrating an example method operable by asurgical robotic system, or component(s) thereof, for detectingcollision or misalignment in accordance with aspects of this disclosure.

FIG. 21 is a flowchart illustrating an example method operable by asurgical robotic system, or component(s) thereof, for detecting acollision in accordance with aspects of this disclosure.

DETAILED DESCRIPTION 1. Overview.

Aspects of the present disclosure may be integrated into arobotically-enabled medical system capable of performing a variety ofmedical procedures, including both minimally invasive, such aslaparoscopy, and non-invasive, such as endoscopy, procedures. Amongendoscopy procedures, the system may be capable of performingbronchoscopy, ureteroscopy, gastroscopy, etc.

In addition to performing the breadth of procedures, the system mayprovide additional benefits, such as enhanced imaging and guidance toassist the physician. Additionally, the system may provide the physicianwith the ability to perform the procedure from an ergonomic positionwithout the need for awkward arm motions and positions. Still further,the system may provide the physician with the ability to perform theprocedure with improved ease of use such that one or more of theinstruments of the system can be controlled by a single user.

Various embodiments will be described below in conjunction with thedrawings for purposes of illustration. It should be appreciated thatmany other implementations of the disclosed concepts are possible, andvarious advantages can be achieved with the disclosed implementations.Headings are included herein for reference and to aid in locatingvarious sections. These headings are not intended to limit the scope ofthe concepts described with respect thereto. Such concepts may haveapplicability throughout the entire specification.

A. Robotic System—Cart.

The robotically-enabled medical system may be configured in a variety ofways depending on the particular procedure. FIG. 1 illustrates anembodiment of a cart-based robotically-enabled system 10 arranged for adiagnostic and/or therapeutic bronchoscopy procedure. During abronchoscopy, the system 10 may comprise a cart 11 having one or morerobotic arms 12 to deliver a medical instrument, such as a steerableendoscope 13, which may be a procedure-specific bronchoscope forbronchoscopy, to a natural orifice access point (i.e., the mouth of thepatient positioned on a table in the present example) to deliverdiagnostic and/or therapeutic tools. As shown, the cart 11 may bepositioned proximate to the patient's upper torso in order to provideaccess to the access point. Similarly, the robotic arms 12 may beactuated to position the bronchoscope relative to the access point. Thearrangement in FIG. 1 may also be utilized when performing agastro-intestinal (GI) procedure with a gastroscope, a specializedendoscope for GI procedures. FIG. 2 depicts an example embodiment of thecart in greater detail.

With continued reference to FIG. 1, once the cart 11 is properlypositioned, the robotic arms 12 may insert the steerable endoscope 13into the patient robotically, manually, or a combination thereof. Asshown, the steerable endoscope 13 may comprise at least two telescopingparts, such as an inner leader portion and an outer sheath portion, eachportion coupled to a separate instrument driver from the set ofinstrument drivers 28, each instrument driver coupled to the distal endof an individual robotic arm. This linear arrangement of the instrumentdrivers 28, which facilitates coaxially aligning the leader portion withthe sheath portion, creates a “virtual rail” 29 that may be repositionedin space by manipulating the one or more robotic arms 12 into differentangles and/or positions. The virtual rails described herein are depictedin the Figures using dashed lines, and accordingly the dashed lines donot depict any physical structure of the system. Translation of theinstrument drivers 28 along the virtual rail 29 telescopes the innerleader portion relative to the outer sheath portion or advances orretracts the endoscope 13 from the patient. The angle of the virtualrail 29 may be adjusted, translated, and pivoted based on clinicalapplication or physician preference. For example, in bronchoscopy, theangle and position of the virtual rail 29 as shown represents acompromise between providing physician access to the endoscope 13 whileminimizing friction that results from bending the endoscope 13 into thepatient's mouth.

The endoscope 13 may be directed down the patient's trachea and lungsafter insertion using precise commands from the robotic system untilreaching the target destination or operative site. In order to enhancenavigation through the patient's lung network and/or reach the desiredtarget, the endoscope 13 may be manipulated to telescopically extend theinner leader portion from the outer sheath portion to obtain enhancedarticulation and greater bend radius. The use of separate instrumentdrivers 28 also allows the leader portion and sheath portion to bedriven independent of each other.

For example, the endoscope 13 may be directed to deliver a biopsy needleto a target, such as, for example, a lesion or nodule within the lungsof a patient. The needle may be deployed down a working channel thatruns the length of the endoscope to obtain a tissue sample to beanalyzed by a pathologist. Depending on the pathology results,additional tools may be deployed down the working channel of theendoscope for additional biopsies. After identifying a nodule to bemalignant, the endoscope 13 may endoscopically deliver tools to resectthe potentially cancerous tissue. In some instances, diagnostic andtherapeutic treatments may need to be delivered in separate procedures.In those circumstances, the endoscope 13 may also be used to deliver afiducial to “mark” the location of the target nodule as well. In otherinstances, diagnostic and therapeutic treatments may be delivered duringthe same procedure.

The system 10 may also include a movable tower 30, which may beconnected via support cables to the cart 11 to provide support forcontrols, electronics, fluidics, optics, sensors, and/or power to thecart 11. Placing such functionality in the tower 30 allows for a smallerform factor cart 11 that may be more easily adjusted and/orre-positioned by an operating physician and his/her staff. Additionally,the division of functionality between the cart/table and the supporttower 30 reduces operating room clutter and facilitates improvingclinical workflow. While the cart 11 may be positioned close to thepatient, the tower 30 may be stowed in a remote location to stay out ofthe way during a procedure.

In support of the robotic systems described above, the tower 30 mayinclude component(s) of a computer-based control system that storescomputer program instructions, for example, within a non-transitorycomputer-readable storage medium such as a persistent magnetic storagedrive, solid state drive, etc. The execution of those instructions,whether the execution occurs in the tower 30 or the cart 11, may controlthe entire system or sub-system(s) thereof. For example, when executedby a processor of the computer system, the instructions may cause thecomponents of the robotics system to actuate the relevant carriages andarm mounts, actuate the robotics arms, and control the medicalinstruments. For example, in response to receiving the control signal,the motors in the joints of the robotics arms may position the arms intoa certain posture.

The tower 30 may also include a pump, flow meter, valve control, and/orfluid access in order to provide controlled irrigation and aspirationcapabilities to system that may be deployed through the endoscope 13.These components may also be controlled using the computer system oftower 30. In some embodiments, irrigation and aspiration capabilitiesmay be delivered directly to the endoscope 13 through separate cable(s).

The tower 30 may include a voltage and surge protector designed toprovide filtered and protected electrical power to the cart 11, therebyavoiding placement of a power transformer and other auxiliary powercomponents in the cart 11, resulting in a smaller, more moveable cart11.

The tower 30 may also include support equipment for the sensors deployedthroughout the robotic system 10. For example, the tower 30 may includeopto-electronics equipment for detecting, receiving, and processing datareceived from the optical sensors or cameras throughout the roboticsystem 10. In combination with the control system, such opto-electronicsequipment may be used to generate real-time images for display in anynumber of consoles deployed throughout the system, including in thetower 30. Similarly, the tower 30 may also include an electronicsubsystem for receiving and processing signals received from deployedelectromagnetic (EM) sensors. The tower 30 may also be used to house andposition an EM field generator for detection by EM sensors in or on themedical instrument.

The tower 30 may also include a console 31 in addition to other consolesavailable in the rest of the system, e.g., console mounted on top of thecart. The console 31 may include a user interface and a display screen,such as a touchscreen, for the physician operator. Consoles in system 10are generally designed to provide both robotic controls as well aspre-operative and real-time information of the procedure, such asnavigational and localization information of the endoscope 13. When theconsole 31 is not the only console available to the physician, it may beused by a second operator, such as a nurse, to monitor the health orvitals of the patient and the operation of system, as well as provideprocedure-specific data, such as navigational and localizationinformation.

The tower 30 may be coupled to the cart 11 and endoscope 13 through oneor more cables or connections (not shown). In some embodiments, thesupport functionality from the tower 30 may be provided through a singlecable to the cart 11, simplifying and de-cluttering the operating room.In other embodiments, specific functionality may be coupled in separatecabling and connections. For example, while power may be providedthrough a single power cable to the cart, the support for controls,optics, fluidics, and/or navigation may be provided through a separatecable.

FIG. 2 provides a detailed illustration of an embodiment of the cartfrom the cart-based robotically-enabled system shown in FIG. 1. The cart11 generally includes an elongated support structure 14 (often referredto as a “column”), a cart base 15, and a console 16 at the top of thecolumn 14. The column 14 may include one or more carriages, such as acarriage 17 (alternatively “arm support”) for supporting the deploymentof one or more robotic arms 12 (three shown in FIG. 2). The carriage 17may include individually configurable arm mounts that rotate along aperpendicular axis to adjust the base of the robotic arms 12 for betterpositioning relative to the patient. The carriage 17 also includes acarriage interface 19 that allows the carriage 17 to verticallytranslate along the column 14.

The carriage interface 19 is connected to the column 14 through slots,such as slot 20, that are positioned on opposite sides of the column 14to guide the vertical translation of the carriage 17. The slot 20contains a vertical translation interface to position and hold thecarriage at various vertical heights relative to the cart base 15.Vertical translation of the carriage 17 allows the cart 11 to adjust thereach of the robotic arms 12 to meet a variety of table heights, patientsizes, and physician preferences. Similarly, the individuallyconfigurable arm mounts on the carriage 17 allow the robotic arm base 21of robotic arms 12 to be angled in a variety of configurations.

In some embodiments, the slot 20 may be supplemented with slot coversthat are flush and parallel to the slot surface to prevent dirt andfluid ingress into the internal chambers of the column 14 and thevertical translation interface as the carriage 17 vertically translates.The slot covers may be deployed through pairs of spring spoolspositioned near the vertical top and bottom of the slot 20. The coversare coiled within the spools until deployed to extend and retract fromtheir coiled state as the carriage 17 vertically translates up and down.The spring-loading of the spools provides force to retract the coverinto a spool when carriage 17 translates towards the spool, while alsomaintaining a tight seal when the carriage 17 translates away from thespool. The covers may be connected to the carriage 17 using, forexample, brackets in the carriage interface 19 to ensure properextension and retraction of the cover as the carriage 17 translates.

The column 14 may internally comprise mechanisms, such as gears andmotors, that are designed to use a vertically aligned lead screw totranslate the carriage 17 in a mechanized fashion in response to controlsignals generated in response to user inputs, e.g., inputs from theconsole 16.

The robotic arms 12 may generally comprise robotic arm bases 21 and endeffectors 22, separated by a series of linkages 23 that are connected bya series of joints 24, each joint comprising an independent actuator,each actuator comprising an independently controllable motor. Eachindependently controllable joint represents an independent degree offreedom available to the robotic arm. Each of the arms 12 have sevenjoints, and thus provide seven degrees of freedom. A multitude of jointsresult in a multitude of degrees of freedom, allowing for “redundant”degrees of freedom. Redundant degrees of freedom allow the robotic arms12 to position their respective end effectors 22 at a specific position,orientation, and trajectory in space using different linkage positionsand joint angles. This allows for the system to position and direct amedical instrument from a desired point in space while allowing thephysician to move the arm joints into a clinically advantageous positionaway from the patient to create greater access, while avoiding armcollisions.

The cart base 15 balances the weight of the column 14, carriage 17, andarms 12 over the floor. Accordingly, the cart base 15 houses heaviercomponents, such as electronics, motors, power supply, as well ascomponents that either enable movement and/or immobilize the cart. Forexample, the cart base 15 includes rollable wheel-shaped casters 25 thatallow for the cart to easily move around the room prior to a procedure.After reaching the appropriate position, the casters 25 may beimmobilized using wheel locks to hold the cart 11 in place during theprocedure.

Positioned at the vertical end of column 14, the console 16 allows forboth a user interface for receiving user input and a display screen (ora dual-purpose device such as, for example, a touchscreen 26) to providethe physician user with both pre-operative and intra-operative data.Potential pre-operative data on the touchscreen 26 may includepre-operative plans, navigation and mapping data derived frompre-operative computerized tomography (CT) scans, and/or notes frompre-operative patient interviews. Intra-operative data on display mayinclude optical information provided from the tool, sensor andcoordinate information from sensors, as well as vital patientstatistics, such as respiration, heart rate, and/or pulse. The console16 may be positioned and tilted to allow a physician to access theconsole from the side of the column 14 opposite carriage 17. From thisposition the physician may view the console 16, robotic arms 12, andpatient while operating the console 16 from behind the cart 11. Asshown, the console 16 also includes a handle 27 to assist withmaneuvering and stabilizing cart 11.

FIG. 3 illustrates an embodiment of a robotically-enabled system 10arranged for ureteroscopy. In a ureteroscopic procedure, the cart 11 maybe positioned to deliver a ureteroscope 32, a procedure-specificendoscope designed to traverse a patient's urethra and ureter, to thelower abdominal area of the patient. In a ureteroscopy, it may bedesirable for the ureteroscope 32 to be directly aligned with thepatient's urethra to reduce friction and forces on the sensitive anatomyin the area. As shown, the cart 11 may be aligned at the foot of thetable to allow the robotic arms 12 to position the ureteroscope 32 fordirect linear access to the patient's urethra. From the foot of thetable, the robotic arms 12 may insert the ureteroscope 32 along thevirtual rail 33 directly into the patient's lower abdomen through theurethra.

After insertion into the urethra, using similar control techniques as inbronchoscopy, the ureteroscope 32 may be navigated into the bladder,ureters, and/or kidneys for diagnostic and/or therapeutic applications.For example, the ureteroscope 32 may be directed into the ureter andkidneys to break up kidney stone build up using laser or ultrasoniclithotripsy device deployed down the working channel of the ureteroscope32. After lithotripsy is complete, the resulting stone fragments may beremoved using baskets deployed down the ureteroscope 32.

FIG. 4 illustrates an embodiment of a robotically-enabled systemsimilarly arranged for a vascular procedure. In a vascular procedure,the system 10 may be configured such the cart 11 may deliver a medicalinstrument 34, such as a steerable catheter, to an access point in thefemoral artery in the patient's leg. The femoral artery presents both alarger diameter for navigation as well as relatively less circuitous andtortuous path to the patient's heart, which simplifies navigation. As ina ureteroscopic procedure, the cart 11 may be positioned towards thepatient's legs and lower abdomen to allow the robotic arms 12 to providea virtual rail 35 with direct linear access to the femoral artery accesspoint in the patient's thigh/hip region. After insertion into theartery, the medical instrument 34 may be directed and inserted bytranslating the instrument drivers 28. Alternatively, the cart may bepositioned around the patient's upper abdomen in order to reachalternative vascular access points, such as, for example, the carotidand brachial arteries near the shoulder and wrist.

B. Robotic System—Table.

Embodiments of the robotically-enabled medical system may alsoincorporate the patient's table. Incorporation of the table reduces theamount of capital equipment within the operating room by removing thecart, which allows greater access to the patient. FIG. 5 illustrates anembodiment of such a robotically-enabled system arranged for abronchoscopy procedure. System 36 includes a support structure or column37 for supporting platform 38 (shown as a “table” or “bed”) over thefloor. Much like in the cart-based systems, the end effectors of therobotic arms 39 of the system 36 comprise instrument drivers 42 that aredesigned to manipulate an elongated medical instrument, such as abronchoscope 40 in FIG. 5, through or along a virtual rail 41 formedfrom the linear alignment of the instrument drivers 42. In practice, aC-arm for providing fluoroscopic imaging may be positioned over thepatient's upper abdominal area by placing the emitter and detectoraround table 38.

FIG. 6 provides an alternative view of the system 36 without the patientand medical instrument for discussion purposes. As shown, the column 37may include one or more carriages 43 shown as ring-shaped in the system36, from which the one or more robotic arms 39 may be based. Thecarriages 43 may translate along a vertical column interface 44 thatruns the length of the column 37 to provide different vantage pointsfrom which the robotic arms 39 may be positioned to reach the patient.The carriage(s) 43 may rotate around the column 37 using a mechanicalmotor positioned within the column 37 to allow the robotic arms 39 tohave access to multiples sides of the table 38, such as, for example,both sides of the patient. In embodiments with multiple carriages, thecarriages may be individually positioned on the column and may translateand/or rotate independent of the other carriages. While carriages 43need not surround the column 37 or even be circular, the ring-shape asshown facilitates rotation of the carriages 43 around the column 37while maintaining structural balance. Rotation and translation of thecarriages 43 allows the system to align the medical instruments, such asendoscopes and laparoscopes, into different access points on thepatient.

The arms 39 may be mounted on the carriages through a set of arm mounts45 comprising a series of joints that may individually rotate and/ortelescopically extend to provide additional configurability to therobotic arms 39. Additionally, the arm mounts 45 may be positioned onthe carriages 43 such that, when the carriages 43 are appropriatelyrotated, the arm mounts 45 may be positioned on either the same side oftable 38 (as shown in FIG. 6), on opposite sides of table 38 (as shownin FIG. 9), or on adjacent sides of the table 38 (not shown).

The column 37 structurally provides support for the table 38, and a pathfor vertical translation of the carriages. Internally, the column 37 maybe equipped with lead screws for guiding vertical translation of thecarriages, and motors to mechanize the translation of said carriagesbased the lead screws. The column 37 may also convey power and controlsignals to the carriage 43 and robotic arms 39 mounted thereon.

The table base 46 serves a similar function as the cart base 15 in cart11 shown in FIG. 2, housing heavier components to balance the table/bed38, the column 37, the carriages 43, and the robotic arms 39. The tablebase 46 may also incorporate rigid casters to provide stability duringprocedures. Deployed from the bottom of the table base 46, the castersmay extend in opposite directions on both sides of the base 46 andretract when the system 36 needs to be moved.

Continuing with FIG. 6, the system 36 may also include a tower (notshown) that divides the functionality of system 36 between table andtower to reduce the form factor and bulk of the table. As in earlierdisclosed embodiments, the tower may be provide a variety of supportfunctionalities to table, such as processing, computing, and controlcapabilities, power, fluidics, and/or optical and sensor processing. Thetower may also be movable to be positioned away from the patient toimprove physician access and de-clutter the operating room.Additionally, placing components in the tower allows for more storagespace in the table base for potential stowage of the robotic arms. Thetower may also include a console that provides both a user interface foruser input, such as keyboard and/or pendant, as well as a display screen(or touchscreen) for pre-operative and intra-operative information, suchas real-time imaging, navigation, and tracking information.

In some embodiments, a table base may stow and store the robotic armswhen not in use. FIG. 7 illustrates a system 47 that stows robotic armsin an embodiment of the table-based system. In system 47, carriages 48may be vertically translated into base 49 to stow robotic arms 50, armmounts 51, and the carriages 48 within the base 49. Base covers 52 maybe translated and retracted open to deploy the carriages 48, arm mounts51, and arms 50 around column 53, and closed to stow to protect themwhen not in use. The base covers 52 may be sealed with a membrane 54along the edges of its opening to prevent dirt and fluid ingress whenclosed.

FIG. 8 illustrates an embodiment of a robotically-enabled table-basedsystem configured for a ureteroscopy procedure. In a ureteroscopy, thetable 38 may include a swivel portion 55 for positioning a patientoff-angle from the column 37 and table base 46. The swivel portion 55may rotate or pivot around a pivot point (e.g., located below thepatient's head) in order to position the bottom portion of the swivelportion 55 away from the column 37. For example, the pivoting of theswivel portion 55 allows a C-arm (not shown) to be positioned over thepatient's lower abdomen without competing for space with the column (notshown) below table 38. By rotating the carriage 35 (not shown) aroundthe column 37, the robotic arms 39 may directly insert a ureteroscope 56along a virtual rail 57 into the patient's groin area to reach theurethra. In a ureteroscopy, stirrups 58 may also be fixed to the swivelportion 55 of the table 38 to support the position of the patient's legsduring the procedure and allow clear access to the patient's groin area.

In a laparoscopic procedure, through small incision(s) in the patient'sabdominal wall, minimally invasive instruments (elongated in shape toaccommodate the size of the one or more incisions) may be inserted intothe patient's anatomy. After inflation of the patient's abdominalcavity, the instruments, often referred to as laparoscopes, may bedirected to perform surgical tasks, such as grasping, cutting, ablating,suturing, etc. FIG. 9 illustrates an embodiment of a robotically-enabledtable-based system configured for a laparoscopic procedure. As shown inFIG. 9, the carriages 43 of the system 36 may be rotated and verticallyadjusted to position pairs of the robotic arms 39 on opposite sides ofthe table 38, such that laparoscopes 59 may be positioned using the armmounts 45 to be passed through minimal incisions on both sides of thepatient to reach his/her abdominal cavity.

To accommodate laparoscopic procedures, the robotically-enabled tablesystem may also tilt the platform to a desired angle. FIG. 10illustrates an embodiment of the robotically-enabled medical system withpitch or tilt adjustment. As shown in FIG. 10, the system 36 mayaccommodate tilt of the table 38 to position one portion of the table ata greater distance from the floor than the other. Additionally, the armmounts 45 may rotate to match the tilt such that the arms 39 maintainthe same planar relationship with table 38. To accommodate steeperangles, the column 37 may also include telescoping portions 60 thatallow vertical extension of column 37 to keep the table 38 from touchingthe floor or colliding with base 46.

FIG. 11 provides a detailed illustration of the interface between thetable 38 and the column 37. Pitch rotation mechanism 61 may beconfigured to alter the pitch angle of the table 38 relative to thecolumn 37 in multiple degrees of freedom. The pitch rotation mechanism61 may be enabled by the positioning of orthogonal axes 1, 2 at thecolumn-table interface, each axis actuated by a separate motor 3, 4responsive to an electrical pitch angle command. Rotation along onescrew 5 would enable tilt adjustments in one axis 1, while rotationalong the other screw 6 would enable tilt adjustments along the otheraxis 2.

For example, pitch adjustments are particularly useful when trying toposition the table in a Trendelenburg position. i.e., position thepatient's lower abdomen at a higher position from the floor than thepatient's lower abdomen, for lower abdominal surgery. The Trendelenburgposition causes the patient's internal organs to slide towards his/herupper abdomen through the force of gravity, clearing out the abdominalcavity for minimally invasive tools to enter and perform lower abdominalsurgical procedures, such as laparoscopic prostatectomy.

C. Instrument Driver & Interface.

The end effectors of the system's robotic arms comprise (i) aninstrument driver (alternatively referred to as “instrument drivemechanism” or “instrument device manipulator” (IDM)) that incorporateelectro-mechanical means for actuating the medical instrument and (ii) aremovable or detachable medical instrument which may be devoid of anyelectro-mechanical components, such as motors. This dichotomy may bedriven by the need to sterilize medical instruments used in medicalprocedures, and the inability to adequately sterilize expensive capitalequipment due to their intricate mechanical assemblies and sensitiveelectronics. Accordingly, the medical instruments may be designed to bedetached, removed, and interchanged from the instrument driver (and thusthe system) for individual sterilization or disposal by the physician orthe physician's staff. In contrast, the instrument drivers need not bechanged or sterilized, and may be draped for protection.

FIG. 12 illustrates an example instrument driver. Positioned at thedistal end of a robotic arm, instrument driver 62 comprises of one ormore drive units 63 arranged with parallel axes to provide controlledtorque to a medical instrument via drive shafts 64. Each drive unit 63comprises an individual drive shaft 64 for interacting with theinstrument, a gear head 65 for converting the motor shaft rotation to adesired torque, a motor 66 for generating the drive torque, an encoder67 to measure the speed of the motor shaft and provide feedback to thecontrol circuitry, and control circuitry 68 for receiving controlsignals and actuating the drive unit. Each drive unit 63 beingindependent controlled and motorized, the instrument driver 62 mayprovide multiple (four as shown in FIG. 12) independent drive outputs tothe medical instrument. In operation, the control circuitry 68 wouldreceive a control signal, transmit a motor signal to the motor 66,compare the resulting motor speed as measured by the encoder 67 with thedesired speed, and modulate the motor signal to generate the desiredtorque.

For procedures that require a sterile environment, the robotic systemmay incorporate a drive interface, such as a sterile adapter connectedto a sterile drape, that sits between the instrument driver and themedical instrument. The chief purpose of the sterile adapter is totransfer angular motion from the drive shafts of the instrument driverto the drive inputs of the instrument while maintaining physicalseparation, and thus sterility, between the drive shafts and driveinputs. Accordingly, an example sterile adapter may comprise of a seriesof rotational inputs and outputs intended to be mated with the driveshafts of the instrument driver and drive inputs on the instrument.Connected to the sterile adapter, the sterile drape, comprised of athin, flexible material such as transparent or translucent plastic, isdesigned to cover the capital equipment, such as the instrument driver,robotic arm, and cart (in a cart-based system) or table (in atable-based system). Use of the drape would allow the capital equipmentto be positioned proximate to the patient while still being located inan area not requiring sterilization (i.e., non-sterile field). On theother side of the sterile drape, the medical instrument may interfacewith the patient in an area requiring sterilization (i.e., sterilefield).

D. Medical Instrument.

FIG. 13 illustrates an example medical instrument with a pairedinstrument driver. Like other instruments designed for use with arobotic system, medical instrument 70 comprises an elongated shaft 71(or elongate body) and an instrument base 72. The instrument base 72,also referred to as an “instrument handle” due to its intended designfor manual interaction by the physician, may generally compriserotatable drive inputs 73, e.g., receptacles, pulleys or spools, thatare designed to be mated with drive outputs 74 that extend through adrive interface on instrument driver 75 at the distal end of robotic arm76. When physically connected, latched, and/or coupled, the mated driveinputs 73 of instrument base 72 may share axes of rotation with thedrive outputs 74 in the instrument driver 75 to allow the transfer oftorque from drive outputs 74 to drive inputs 73. In some embodiments,the drive outputs 74 may comprise splines that are designed to mate withreceptacles on the drive inputs 73.

The elongated shaft 71 is designed to be delivered through either ananatomical opening or lumen, e.g., as in endoscopy, or a minimallyinvasive incision. e.g., as in laparoscopy. The elongated shaft 66 maybe either flexible (e.g., having properties similar to an endoscope) orrigid (e.g., having properties similar to a laparoscope) or contain acustomized combination of both flexible and rigid portions. Whendesigned for laparoscopy, the distal end of a rigid elongated shaft maybe connected to an end effector comprising a jointed wrist formed from aclevis with an axis of rotation and a surgical tool, such as, forexample, a grasper or scissors, that may be actuated based on force fromthe tendons as the drive inputs rotate in response to torque receivedfrom the drive outputs 74 of the instrument driver 75. When designed forendoscopy, the distal end of a flexible elongated shaft may include asteerable or controllable bending section that may be articulated andbent based on torque received from the drive outputs 74 of theinstrument driver 75.

Torque from the instrument driver 75 is transmitted down the elongatedshaft 71 using tendons within the shaft 71. These individual tendons,such as pull wires, may be individually anchored to individual driveinputs 73 within the instrument handle 72. From the handle 72, thetendons are directed down one or more pull lumens within the elongatedshaft 71 and anchored at the distal portion of the elongated shaft 71.In laparoscopy, these tendons may be coupled to a distally mounted endeffector, such as a wrist, grasper, or scissor. Under such anarrangement, torque exerted on drive inputs 73 would transfer tension tothe tendon, thereby causing the end effector to actuate in some way. Inlaparoscopy, the tendon may cause a joint to rotate about an axis,thereby causing the end effector to move in one direction or another.Alternatively, the tendon may be connected to one or more jaws of agrasper at distal end of the elongated shaft 71, where tension from thetendon cause the grasper to close.

In endoscopy, the tendons may be coupled to a bending or articulatingsection positioned along the elongated shaft 71 (e.g., at the distalend) via adhesive, control ring, or other mechanical fixation. Whenfixedly attached to the distal end of a bending section, torque exertedon drive inputs 73 would be transmitted down the tendons, causing thesofter, bending section (sometimes referred to as the articulablesection or region) to bend or articulate. Along the non-bendingsections, it may be advantageous to spiral or helix the individual pulllumens that direct the individual tendons along (or inside) the walls ofthe endoscope shaft to balance the radial forces that result fromtension in the pull wires. The angle of the spiraling and/or spacingthere between may be altered or engineered for specific purposes,wherein tighter spiraling exhibits lesser shaft compression under loadforces, while lower amounts of spiraling results in greater shaftcompression under load forces, but also exhibits limits bending. On theother end of the spectrum, the pull lumens may be directed parallel tothe longitudinal axis of the elongated shaft 71 to allow for controlledarticulation in the desired bending or articulable sections.

In endoscopy, the elongated shaft 71 houses a number of components toassist with the robotic procedure. The shaft may comprise of a workingchannel for deploying surgical tools, irrigation, and/or aspiration tothe operative region at the distal end of the shaft 71. The shaft 71 mayalso accommodate wires and/or optical fibers to transfer signals to/froman optical assembly at the distal tip, which may include of an opticalcamera. The shaft 71 may also accommodate optical fibers to carry lightfrom proximally-located light sources, such as light emitting diodes, tothe distal end of the shaft.

At the distal end of the instrument 70, the distal tip may also comprisethe opening of a working channel for delivering tools for diagnosticand/or therapy, irrigation, and aspiration to an operative site. Thedistal tip may also include a port for a camera, such as a fiberscope ora digital camera, to capture images of an internal anatomical space.Relatedly, the distal tip may also include ports for light sources forilluminating the anatomical space when using the camera.

In the example of FIG. 13, the drive shaft axes, and thus the driveinput axes, are orthogonal to the axis of the elongated shaft. Thisarrangement, however, complicates roll capabilities for the elongatedshaft 71. Rolling the elongated shaft 71 along its axis while keepingthe drive inputs 73 static results in undesirable tangling of thetendons as they extend off the drive inputs 73 and enter pull lumenswithin the elongate shaft 71. The resulting entanglement of such tendonsmay disrupt any control algorithms intended to predict movement of theflexible elongate shaft during an endoscopic procedure.

FIG. 14 illustrates an alternative design for an instrument driver andinstrument where the axes of the drive units are parallel to the axis ofthe elongated shaft of the instrument. As shown, a circular instrumentdriver 80 comprises four drive units with their drive outputs 81 alignedin parallel at the end of a robotic arm 82. The drive units, and theirrespective drive outputs 81, are housed in a rotational assembly 83 ofthe instrument driver 80 that is driven by one of the drive units withinthe assembly 83. In response to torque provided by the rotational driveunit, the rotational assembly 83 rotates along a circular bearing thatconnects the rotational assembly 83 to the non-rotational portion 84 ofthe instrument driver. Power and controls signals may be communicatedfrom the non-rotational portion 84 of the instrument driver 80 to therotational assembly 83 through electrical contacts may be maintainedthrough rotation by a brushed slip ring connection (not shown). In otherembodiments, the rotational assembly 83 may be responsive to a separatedrive unit that is integrated into the non-rotatable portion 84, andthus not in parallel to the other drive units. The rotational mechanism83 allows the instrument driver 80 to rotate the drive units, and theirrespective drive outputs 81, as a single unit around an instrumentdriver axis 85.

Like earlier disclosed embodiments, an instrument 86 may comprise of anelongated shaft portion 88 and an instrument base 87 (shown with atransparent external skin for discussion purposes) comprising aplurality of drive inputs 89 (such as receptacles, pulleys, and spools)that are configured to receive the drive outputs 81 in the instrumentdriver 80. Unlike prior disclosed embodiments, instrument shaft 88extends from the center of instrument base 87 with an axis substantiallyparallel to the axes of the drive inputs 89, rather than orthogonal asin the design of FIG. 13.

When coupled to the rotational assembly 83 of the instrument driver 80,the medical instrument 86, comprising instrument base 87 and instrumentshaft 88, rotates in combination with the rotational assembly 83 aboutthe instrument driver axis 85. Since the instrument shaft 88 ispositioned at the center of instrument base 87, the instrument shaft 88is coaxial with instrument driver axis 85 when attached. Thus, rotationof the rotational assembly 83 causes the instrument shaft 88 to rotateabout its own longitudinal axis. Moreover, as the instrument base 87rotates with the instrument shaft 88, any tendons connected to the driveinputs 89 in the instrument base 87 are not tangled during rotation.Accordingly, the parallelism of the axes of the drive outputs 81, driveinputs 89, and instrument shaft 88 allows for the shaft rotation withouttangling any control tendons.

E. Navigation and Control.

Traditional endoscopy may involve the use of fluoroscopy (e.g., as maybe delivered through a C-arm) and other forms of radiation-based imagingmodalities to provide endoluminal guidance to an operator physician. Incontrast, the robotic systems contemplated by this disclosure canprovide for non-radiation-based navigational and localization means toreduce physician exposure to radiation and reduce the amount ofequipment within the operating room. As used herein, the term“localization” may refer to determining and/or monitoring the positionof objects in a reference coordinate system. Technologies such aspre-operative mapping, computer vision, real-time EM tracking, and robotcommand data may be used individually or in combination to achieve aradiation-free operating environment. In other cases, whereradiation-based imaging modalities are still used, the pre-operativemapping, computer vision, real-time EM tracking, and robot command datamay be used individually or in combination to improve upon theinformation obtained solely through radiation-based imaging modalities.

FIG. 15 is a block diagram illustrating a localization system 90 thatestimates a location of one or more elements of the robotic system, suchas the location of the instrument, in accordance to an exampleembodiment. The localization system 90 may be a set of one or morecomputer devices configured to execute one or more instructions. Thecomputer devices may be embodied by a processor (or processors) andcomputer-readable memory in one or more components discussed above. Byway of example and not limitation, the computer devices may be in thetower 30 shown in FIG. 1, the cart shown in FIGS. 1-4, the beds shown inFIGS. 5-10, etc.

As shown in FIG. 15, the localization system 90 may include alocalization module 95 that processes input data 91-94 to generatelocation data 96 for the distal tip of a medical instrument. Thelocation data 96 may be data or logic that represents a location and/ororientation of the distal end of the instrument relative to a frame ofreference. The frame of reference can be a frame of reference relativeto the anatomy of the patient or to a known object, such as an EM fieldgenerator (see discussion below for the EM field generator).

The various input data 91-94 are now described in greater detail.Pre-operative mapping may be accomplished through the use of thecollection of low dose CT scans. Pre-operative CT scans generatetwo-dimensional images, each representing a “slice” of a cutaway view ofthe patient's internal anatomy. When analyzed in the aggregate,image-based models for anatomical cavities, spaces and structures of thepatient's anatomy, such as a patient lung network, may be generated.Techniques such as center-line geometry may be determined andapproximated from the CT images to develop a three-dimensional volume ofthe patient's anatomy, referred to as preoperative model data 91. Theuse of center-line geometry is discussed in U.S. patent application Ser.No. 14/523,760, the contents of which ae herein incorporated in itsentirety. Network topological models may also be derived from theCT-images, and are particularly appropriate for bronchoscopy.

In some embodiments, the instrument may be equipped with a camera toprovide vision data 92. The localization module 95 may process thevision data to enable one or more vision-based location tracking. Forexample, the preoperative model data may be used in conjunction with thevision data 92 to enable computer vision-based tracking of the medicalinstrument (e.g., an endoscope or an instrument advance through aworking channel of the endoscope). For example, using the preoperativemodel data 91, the robotic system may generate a library of expectedendoscopic images from the model based on the expected path of travel ofthe endoscope, each image linked to a location within the model.Intra-operatively, this library may be referenced by the robotic systemin order to compare real-time images captured at the camera (e.g., acamera at a distal end of the endoscope) to those in the image libraryto assist localization.

Other computer vision-based tracking techniques use feature tracking todetermine motion of the camera, and thus the endoscope. Some feature ofthe localization module 95 may identify circular geometries in thepreoperative model data 91 that correspond to anatomical lumens andtrack the change of those geometries to determine which anatomical lumenwas selected, as well as the relative rotational and/or translationalmotion of the camera. Use of a topological map may further enhancevision-based algorithms or techniques.

Optical flow, another computer vision-based technique, may analyze thedisplacement and translation of image pixels in a video sequence in thevision data 92 to infer camera movement. Through the comparison ofmultiple frames over multiple iterations, movement and location of thecamera (and thus the endoscope) may be determined.

The localization module 95 may use real-time EM tracking to generate areal-time location of the endoscope in a global coordinate system thatmay be registered to the patient's anatomy, represented by thepreoperative model. In EM tracking, an EM sensor (or tracker) comprisingof one or more sensor coils embedded in one or more locations andorientations in a medical instrument (e.g., an endoscopic tool) measuresthe variation in the EM field created by one or more static EM fieldgenerators positioned at a known location. The location informationdetected by the EM sensors is stored as EM data 93. The EM fieldgenerator (or transmitter), may be placed close to the patient to createa low intensity magnetic field that the embedded sensor may detect. Themagnetic field induces small currents in the sensor coils of the EMsensor, which may be analyzed to determine the distance and anglebetween the EM sensor and the EM field generator. These distances andorientations may be intra-operatively “registered” to the patientanatomy (e.g., the preoperative model) in order to determine thegeometric transformation that aligns a single location in the coordinatesystem with a position in the pre-operative model of the patient'sanatomy. Once registered, an embedded EM tracker in one or morepositions of the medical instrument (e.g., the distal tip of anendoscope) may provide real-time indications of the progression of themedical instrument through the patient's anatomy.

Robotic command and kinematics data 94 may also be used by thelocalization module 95 to provide localization data 96 for the roboticsystem. Device pitch and yaw resulting from articulation commands may bedetermined during pre-operative calibration. Intra-operatively, thesecalibration measurements may be used in combination with known insertiondepth information to estimate the position of the instrument.Alternatively, these calculations may be analyzed in combination withEM, vision, and/or topological modeling to estimate the position of themedical instrument within the network.

As FIG. 15 shows, a number of other input data can be used by thelocalization module 95. For example, although not shown in FIG. 15, aninstrument utilizing shape-sensing fiber can provide shape data that thelocalization module 95 can use to determine the location and shape ofthe instrument.

The localization module 95 may use the input data 91-94 incombination(s). In some cases, such a combination may use aprobabilistic approach where the localization module 95 assigns aconfidence weight to the location determined from each of the input data91-94. Thus, where the EM data may not be reliable (as may be the casewhere there is EM interference) the confidence of the locationdetermined by the EM data 93 can be decrease and the localization module95 may rely more heavily on the vision data 92 and/or the roboticcommand and kinematics data 94.

As discussed above, the robotic systems discussed herein may be designedto incorporate a combination of one or more of the technologies above.The robotic system's computer-based control system, based in the tower,bed and/or cart, may store computer program instructions, for example,within a non-transitory computer-readable storage medium such as apersistent magnetic storage drive, solid state drive, or the like, that,upon execution, cause the system to receive and analyze sensor data anduser commands, generate control signals throughout the system, anddisplay the navigational and localization data, such as the position ofthe instrument within the global coordinate system, anatomical map, etc.

2. Techniques for Robotic Arm Collision Detection.

Embodiments of the disclosure relate to systems and techniques for thedetection of undesirable forces occurring with respect to one or morerobotic arms of a surgical robotic system. The detection of undesirableforce events may be an important factor in the overall safety of thesurgical robotic system. For example, if a robotic arm collides with anobject during a medical procedure, the collision may result inunexpected forces being applied to the robotic arm, which may affect theposition and/or force applied to a steerable instrument located in thepatient. Thus, it is important to detect robotic arm collisions andappropriately respond to the collisions to prevent harm to the patient.

As used herein, the term “collision” may generally refer to contactbetween two or more objects. A collision may occur between two roboticarms and/or between a robotic arm and another object in the operatingenvironment (e.g., a platform, a cart, a C-arm, etc.). Another source ofunexpected or undesirable force(s) at one or more robotic arms may alsobe misalignment between two robotic arms. While misalignment may notinvolve a collision between the two robotic arms, misalignment mayresult in similar unexpected forces, and thus it may also be importantto detect misalignment for the overall safety of the surgical roboticsystem.

The system may take one or more actions in response to the detection ofa collision or misalignment. For example, the system may provide anindication of the detected event (e.g., collision or misalignment) to auser of the system. The indication of the detected event to the user maybe provided via one or more output devices, including a display device,a haptic feedback device, an audio device, etc. The system may alsodiscontinue the medical procedure until the collision or misalignmentevent has been resolved.

A. Example System for Detecting Collision and Misalignment.

FIG. 16 illustrates an embodiment of a cart-based surgical roboticsystem which may be configured to detect robotic arm collision and/ormisalignment in accordance with aspects of this disclosure. AlthoughFIG. 16 is directed to an embodiment in which the robotic arm(s) areattached to a cart, this disclosure is not limited thereto, and thetechniques described herein are be applicable robotic arm(s) which maybe attached to a column supporting a patient platform as shown in FIG.6.

Returning to FIG. 16, provided is a system 100 that may include a cart105, one or more robotic arm(s) 110 and 120, and a steerable instrument130. The cart 105 may include a processor (not illustrated), a memory(not illustrated), and a display 107 configured to render encoded dataindicative of a detected collision and/or misalignment event. However,depending on the embodiment, one or more of the processor, the memory,and the display 107 may be located on or within another device, such ason the moveable tower 30 illustrated in FIG. 1. Additionally, in otherimplementations, a feedback device other than the display 107 may beused in place of, or in addition to, the display 107. Other feedbackdevices which may be employed include haptic devices, speakers,force-feedback actuated via one or more of the robotic arm(s) 112, oneor more light-emitting diode(s) LED(s), etc.

The robotic arm(s) 110 and 120 may include a first robotic arm 110 and asecond robotic arm 120, respectively. However, aspects of thisdisclosure are also applicable to system having a greater or fewernumber of robotic arms. In the embodiment of FIG. 16, the first roboticarm 110 includes a plurality of linkages 111, a plurality of joints 113,and an IDM 115. Each of the joints 113 connects two adjacent linkages111. Although not illustrated, the first robotic arm 110 may alsoinclude a torque sensor configured to detect torque between two of thelinkages 111. In certain implementations, a given joint 113 may house acorresponding torque sensor configured to detect torque between the twolinkages 111 adjacent to the given joint 111. A torque sensor may alsobe provided in the joint 113 that connects the first robotic arm 110 tothe cart 105. In certain implementations, the torque sensor(s) may beimplemented via a plurality of strain gauges configured to minimize theeffects of torques that are not along the axis of rotation of thecorresponding joint 113 from affecting the output of the torque sensor.

Additionally, a given joint 113 may further house a motor (notillustrated) configured to apply a force between the two adjacentlinkages 111 to the given joint 113 in order to adjust the positioningof the two adjacent linkages 111. The IDM 115 may be connected to adistal end of the robotic arm 110. By actuating the motor(s) in one ormore of the joints 113 of the first robotic arm 110, the motor(s) may beoperable to adjust the posture or pose of the first robotic arm 110, andthus the IDM 115 (e.g., by adjusting the position and/or orientation ofone or more joints 113 of the first arm) and thereby control a steerableinstrument 130 attached to the IDM 115.

Each of the joints 113 may further house a position sensor configured tomeasure the relative position of the two adjacent linkages 111. Thus, agiven joint 113 may further house the position sensor, which may beconfigured to measure the angle between the two adjacent linkages 111.The system may be able to determine the position of each of the linkages111 in the first robotic arm 110 based on the output of each of theposition sensors. Additionally, as discussed below, the output of theposition sensors may be used to determine a force applied to a referencepoint on the first robotic arm 110. In certain embodiments, a givenposition sensor may include an encoder. The encoder may be configured tomeasure the speed and/or position of the motor shaft by reading, forexample, coded visual information printed on the motor shaft and mayprovide feedback to the system representative of the speed and/orposition of the motor.

Similar to the first robotic arm 110, the second robotic arm 120 mayinclude a plurality of linkages 121, a plurality of joints 123connecting adjacent linkages 121, and an IDM 125. Each of the joints 123may house a corresponding torque sensor and motor (not illustrated). TheIDM 125 may also be attached to the second medical instrument 133 tooperate the steerable instrument 130.

In certain embodiments, rather than including separate torque sensorsand motors in each of the joints 113 and 123, the motors may alsofunction as torque sensors. For example, when a force is applied to thefirst robotic arm 110 (e.g., the force of gravity, the force of acollision, a force exerted by a user, etc.), the motor(s) may beconfigured to apply opposite and opposing force(s) to the joint 113 tomaintain the position of the first robotic arm 110. The current requiredin the motor(s) to maintain the first robotic arm 110 position maycorrespond to the torque applied to the corresponding joints 113.

The steerable instrument 130 in the FIG. 16 embodiment comprises a firstmedical instrument 131 attached to the IDM 115 of the first robotic arm110 and a second medical instrument 133 attached to the IDM 125 of thesecond robotic arm 120. However, the illustrated example in FIG. 16 ismerely one example steerable instrument 130 and other embodiments mayinclude a steerable instrument 130 that is controlled by a singlerobotic arm 110 or a steerable instrument 130 that requires three ormore robotic arms for operation. Depending on the embodiment and themedical procedure being performed, each of the first and second medicalinstruments may comprise one of an inner leader portion, an outer sheathportion, a needle, forceps, a brush, etc.

The first and second medical instruments 131 and 133 may be configuredto be advanced/inserted into (or retracted from) a patient along a firstaxis 140. As discussed above, the first axis 140 may be termed a virtualrail. The virtual rail may be defined by the axis of alignment of theIDMs 115 and 125. Movement of the IDMs 115 and 125 along the virtualrail may control the advancing and retracting of the first and secondmedical instruments 131 and 133 into and out of the patient. As shown inFIG. 16, a coordinate system may be defined with respect to the firstaxis 140. For example, the first axis 140 (e.g., the virtual rail oraxis of insertion) may be defined along a Y-axis, the Z-axis may bedefined based on the direction of gravity (e.g., substantiallyperpendicular to the first axis 140), and the X-axis may be selectedperpendicular to the Y-Z plane. However, depending on the procedure, theaxis of insertion 140 may not correspond to a horizontal axisperpendicular to the direction of gravity. The coordinate system of therobotic arms may be selected in any manner without departing from thescope of this disclosure.

B. Determination of Force Applied to Robotic Arm(s) and CollisionDetection.

One technique for detecting collisions or misalignment of the roboticarm(s) is to analyze the forces experience by the robotic arm(s). Forexample, while the robotic arm(s) are stationary, the only expectedforce on the arm(s) is the force due to gravity. Accordingly, any forceexperienced by the robotic arm(s) that is inconsistent with the expectedforce due to gravity (e.g., when the difference between the expectedforce and the measured force is greater than a threshold value) may beindicative of a collision between at least one of the robotic arm(s) andanother object.

Certain surgical robotic systems may incorporate a force sensor in eachof the robotic arms to measure the force experienced at a referencepoint on the corresponding robotic arm. For example, a force sensor maybe positioned on or near (e.g., within a defined distance of) the IDM115 of the first robotic arm 110 of FIG. 16 to measure the forcesapplied to the IDM 115. However, force sensors that are able to directlymeasure the applied force at the IDM 115 (e.g., the force sensor islocated at the IDM 115) with the required accuracy may be relativelycostly. Thus, in certain implementations, the system may determine theforce at the IDM 115 (or any reference point on the robotic arm 110)using torque values output from the torque sensors located within thejoints 113.

FIG. 17 is a flowchart which illustrates an example procedure fordetermining a force applied to a robotic arm and detecting a collisionin accordance with aspects of this disclosure. The method 1700illustrated in FIG. 17 is merely an example implementation and themethod 1700 may be modified by adding, removing, and or modifying one ormore of the blocks associated with the method 1700. For convenience,method 1700 will be described as being performed by a system (e.g., thesurgical robotic system 100 of FIG. 16). However, certain aspects of themethod 1700 may be performed, for example, by one or more processors ofthe system based on computer-executable instructions stored in memory.Further, the method 1700 will be described in connection with a singlerobotic arm. However, a similar method may be performed to determine theforce experienced by multiple robotic arms included in the system.

The method 1700 begins at block 1701. At block 1705, the system receivesrobotic arm torque and position values. The system may receive torquevalues from each of the torque sensors included in the robotic arm.Further, the system may retrieve position values from position datastored in memory that indicate the position of each of the linkages inthe robotic arm. For example, the robotic arms may further include anencoder formed on each of the joints. The encoder may measure the speedand/or position of the motor shaft by reading coded visual informationprinted on the motor shaft and may provide feedback to the systemrepresentative of the speed and/or position of the motor. The system maybe configured to determine the position of each of the joints based onthe feedback from the encoders. Using the information from each of theencoders positions on the robotic arm, the system can determine toposition of each of the linkages and the IDM.

At block 1710, the system determines a gravity-compensated torque valuefor each of the joints based on the torque values and position values.The gravity-compensated torque value for a given joint may represent thecomponent of the torque at the joint that is due to forces other thanthe force of gravity. In one implementation, the system may measure afirst torque value at a joint based on the output of the correspondingtorque sensor. The system may then determine a second torque value atthe joint based on the position of the robotic arm. The position data ofthe robotic arm may include data that enables the system to determinethe position of the two linkages connected by the joint and the angleformed therebetween. The second torque value may be indicative of agravitational component of the torque between the two linkages. Thesystem may then be able to determine the gravity-compensated torquevalue based on the first and second torque values. For example, thedifference between the first and second torque values may correspond tothe gravity-compensated torque value.

At block 1715, the system may determine the force exerted on the roboticarm based on the gravity-compensated torque values for each of thejoints. The determined force may therefore exclude the component of theforces experienced by the robotic arm due to gravity. An example of onetechnique for determining the gravity-compensated torque value and theforce applied at a reference point on the robotic arm will be discussedin connection with FIG. 18 below.

At block 1720, the system may detect a collision based on the determinedforce. For example, when the force exceeds a threshold value, the systemmay determine that the robotic arm has collided with another object. Incertain implementations, the system may also determine whether therobotic arm is misaligned with another robotic arm based on thedetermined force. At block 1725, the system may provide an indication ofthe detected collision to a user of the system. For example, in responseto determining that the force exceeds the threshold value, the systemmay notify the user that a collision has been detected. Further, inresponse to detecting misalignment, the system may also provide anindication of the detected misalignment to the user. The method 1700ends at block 1730.

C. Robotic Arm Free-Body Diagram.

FIG. 18 illustrates a free-body diagram of a robotic arm for describingtechniques for calculating forces applied to the robotic arm inaccordance with aspects of this disclosure. The robotic arm 210 may beattached to a cart 211. The robotic arm 210 may include a first linkage230, a first joint 240 connecting the first linkage 230 to the cart 211,a second linkage 235, a second joint 245 connecting the first and secondlinkages 230 and 235, and an IDM 250 connected to the distal end of thesecond linkage 235. The robotic arm 210 is illustrated in a simplifiedform in FIG. 18; however, more complex robotic arms may be analyzed in asimilar manner by adding additional linkages to the arm connected byadditional joints. The IDM 250 may define a reference point at which anexternal force F is modeled as being applied to the robotic arm 210.However, in other embodiments, the reference point may be set to anyother point along the robotic arm 210. Additionally, the force due togravity experienced by each of the first and second linkages 230 and 235is illustrated in the diagram as a gravity force vector g applied at thecenter of gravity of the corresponding linkage 230 and 235.

Each of the joints 240 and 245 may include a torque sensor configured tooutput a measured torque value τ_(measured). The measured torque valueτ_(measured) at each of the joints 240 and 245 may be determinedaccording to the following equation:

τ_(measured)=τ_(force)+τ_(gravity)  (1)

where τ_(measured) is the measured torque value, τ_(force) is the torqueat the joint 240 or 245 due to the force F applied to the robotic arm210, and τ_(gravity) is the torque applied to joint 240 or 245 due tothe force of gravity g. In this embodiment, the force F applied to therobotic arm 210 is modelled as being applied to the IDM 250 as areference point. However, the force may be modelled as being applied tothe robotic arm 210 at difference points depending on the embodiment.

The torque due to the force F applied at the reference point and thetorque due to gravity g may be determined as follows:

τ_(force) =J(θ)^(T) F  (2)

τ_(gravity) =G(θ,g)  (3)

where J(θ)^(T) is a Jacobian transpose matrix that represents thetransmission of the force F to the joint 240 or 245 based on thepositions of the joints 240 or 245 in the robotic arm 210 and G(θ, g)represents the transmission of torque to the joints 240 or 245 due togravity g. Substituting equations (2) and (3) into (1) gives:

τ_(measured) =J(θ)^(T) F+G(θ,g)  (4)

Accordingly, the force F applied to the reference point (e.g., the IDM250) can be solved based on the measured torques τ_(measured), theJacobian transpose matrix J(θ)^(T), and the transmission of torque dueto gravity G(θ, g).

D. Collision and Misalignment Detection.

Once the force(s) at a reference point on one or more robotic arms havebeen determined, the system may determine whether a collision ormisalignment event has occurred based on the force(s). Thisdetermination may be based on whether the determined force(s) areconsistent with the expected forces at the reference points.

When a robotic arm is stationary, the expected value of agravity-compensated force (e.g., the determined force in which thecomponent of the force due to gravity has been removed) is zero. Thatis, under normal circumstances, there is no force expected to be appliedto the arm other than the force due to gravity when the robotic arm isstationary. As such, when the robotic arm is stationary, the system maycompare the force to a threshold value. If the gravity-compensated forceis greater than the threshold value, the system may determine that anobject has collided with the robotic arm.

In certain implementations, the system may determine the components ofthe force in each of the X, Y, and Z-axes. The system may, at a certainfrequency, determine the components of the force during a medicalprocedure. The expected values of the force may depend on the medicalprocedure being performed. For example, while a medical instrument isbeing advanced into a patient along the Y-axis (which may correspond toa first axis 140 or axis of insertion, see FIG. 16), the IDM mayexperience a resistance to the insertion as a force along the Y-axis. Asimilar resistance force along the Y-axis may be generated when themedical instrument is retracted from the patient. Thus, forces along theY-axis during insertion or retraction of the medical device may notnecessarily be indicative of a collision. For example, the system maycompare the external force direction to the actual insertion directionof the medical instrument to determine whether the force is consistentwith normal operation of the robotic arm (e.g., the force is insubstantially the same direction as the actual insertion direction) orthe force is consistent with collision with an external object (e.g., atleast a portion of the force is in a direction other than the actualinsertion direction).

FIG. 19A is a graph illustrating an example of the forces measuredduring insertion of a medical instrument in accordance with aspects ofthis disclosure. In the example graph, a first instrument ismoved/driven by a first robotic arm from 5,000 ms to 18.000 ms and asecond instrument is driven by a second robotic arm from 18.000 ms to34,000 ms. The illustrated X, Y, and Z-components of the force aremeasured in the second robotic arm. As shown in FIG. 19A, each of the X,Y, and Z-components of the force has a magnitude that is less than 10 N.The Y-axis component of the force measured by the second robotic arm hasa value between about 3 N and 5 N during driving of the second medicalinstrument (e.g., between 18,000 ms and 34.000 ms). The X-axis andZ-axis components of the force may be caused due to minor misalignments(e.g., misalignments within expected tolerances) or due to forcesexerted on the medical instrument due to the path taken by the medicalinstrument within one of the patient's luminal networks which may betransmitted back to the IDM via the medical instrument. The X-axis andZ-axis components of the force may also result from inaccuracy of amodel of the effects due to gravity on the second robotic arm based onthe second robotic arm's current position.

Additionally, the X and Z-components of the force may be correlated withthe Y-component of the force or changes in the configuration of themedical instrument as the medical instrument is being driven. That is,changes in the X and Z-components of the force may occur when driving ofthe medical instrument starts or stops (e.g., when the Y-component ofthe force transitions to or from about 0 N). Further, when the directionof insertion of the distal end of the medical instrument changes, theforce transmitted back to the IDM from the medical instrument may alsochange.

FIG. 19B is a graph illustrating an example of the forces measuredduring insertion of a medical instrument which may be indicative of acollision event in accordance with aspects of this disclosure. As shownin FIG. 19B, at least one of the X, Y. and Z-components of the forceincludes a sharp spike which is consistent with a collision eventbetween the robotic arm and another object. The collision forces may besignificantly greater than the forces experienced during normalinsertion of the medical instrument. Here, when the system detects thatone of the forces is greater than a threshold value, the system maydetermine that the robotic arm has collided with another object. In FIG.19B, collision events may be detected by the system at about times18.000 ms, 22,000 ms, 24,000 ms, 35,000 ms, 38.000 ms, and 42,000 ms.

FIG. 19C is a graph illustrating an example of the forces measuredduring insertion of a medical instrument which may be indicative of amisalignment event in accordance with aspects of this disclosure. Asshown in FIG. 19C, changes in the X and Z-components of the force maynot be directly correlated with the timing of starting and stoppinginsertion of the medical instrument into the patient. However, thesenon-correlated changes may also be consistent with changes in the forcetransmitted back through the medical instrument (e.g., due to changes inthe configuration of the medical instrument). Thus, in certainimplementations, the system may be further configured to distinguishbetween forces caused due to misalignment from expected changes in the Xand Z-components of the force which may be consistent with normaldriving of the medical instrument.

Referring back to FIG. 16, a medical instrument such as, for example,the steerable instrument 130 may include a first medical instrument 131attached to a first IDM 115 of the first robotic arm 110 and a secondmedical instrument 133 attached to a second IDM 125 of the secondrobotic arm 120. The first medical instrument 131 may define a workingchannel through which the second medical instrument 133 is configured tobe advanced and/or retracted. Accordingly, the first robotic arm 110 maybe configured to advance the first medical instrument 131 into thepatient along the first axis 140 (e.g., the Y-axis) and the secondrobotic arm 120 may be configured to advance the second medicalinstrument 133 into the patient, via the working channel, along thefirst axis 140. Similarly, the first robotic arm 110 may be configuredto retract the first medical instrument 131 from the patient along thefirst axis 140 (e.g., the Y-axis) and the second robotic arm 120 may beconfigured to retract the second medical instrument 133 from thepatient, via the working channel, along the first axis 140.

If the first IDM 115 and the second IDM 125 are not properly alignedalong the first axis 140, a force may be generated between the first andsecond IDMs 115 and 125 in the direction of misalignment in the X-Zplane. Accordingly, the first IDM 115 and the second IDM 125 mayexperience opposite and opposing forces in the X-Z plane due to themisalignment of the first and second IDMs 115 and 125. Further, theforces caused due to misalignment may only be generated while drivingone or more of the first and second medical instruments 131 and 133(e.g., while advancing/inserting the second medical instrument 133 orretracting the first medical instrument 131).

In order to detect a misalignment event, the system may be configured todetect a second force at the second IDM 125 of the second robotic arm120. The system may determine that at least one of the first forcemeasured at the first IDM 115 and the second force measured at thesecond IDM 125 is greater than a threshold force. The system may furtherdetermine that that the first and second robotic arms 110 and 120 aremisaligned in response to determining that both of the first and secondforces are greater than the threshold force.

E. Example Collision and Misalignment Detection Technique.

In one example implementation, the surgical robotic system may beconfigured to detect both collision and misalignment events and providean indication to a user that an event has been detected. FIG. 20 is aflowchart illustrating an example method operable by a surgical roboticsystem, or component(s) thereof, for detecting collision or misalignmentin accordance with aspects of this disclosure. For example, the steps ofmethod 2000 illustrated in FIG. 20 may be performed by a processorand/or other component(s) of a surgical robotic system. For convenience,the method 2000 is described as performed by the processor of thesystem.

The method 2000 begins at block 2001. At block 2105 the processordetermines forces at IDMs of first and second robotic arms. For example,the processor may determine a first force at a first IDM of the firstrobotic arm and determine a second force at a second IDM of the secondrobotic arm. The processor may determine the forces based on: i) outputreceived from torque sensors located at each of the joints of the firstand second robotic arms and ii) positions of the first and secondrobotic arms. The first and second forces may be adjusted to remove theforces experienced by the first and second robotic arms due to gravity.

At block 2010, the processor determines whether at least one of thefirst and second forces is indicative of a collision. For example, theprocessor may determine whether the first robotic arm has collided withan object based on the first force at the first IDM. Similarly, theprocessor may determine whether the second robotic arm has collided withan object based on the second force at the second IDM.

In one implementation, the first and/or second robotic arms may beconfigured to advance a steerable instrument into a patient by movementof the first and/or second IDMs along a first axis. The processor maydetermine a first component of the first force applied to the first IDMalong a second axis perpendicular to the first axis. The processor maydetermine that the first component of the first force is greater than afirst threshold value. Thus, the processor may determine that the firstrobotic arm has collided with an object based on determining that thefirst component of the first force is greater than the first thresholdvalue. Since forces along an axis perpendicular to the axis of insertion(e.g., the first axis) are expected to be less than the threshold value,the processor may interpret components of the first force along theperpendicular axis that are greater than the first threshold value to beindicative of a collision. The processor may perform a similar procedureto determine whether the second robotic arm has collided with an object.

The processor may also compare the component of the force along thefirst axis of insertion to a second threshold. For example, theprocessor may determine a second component of the first force applied tothe IDM along the first axis and determine that the second component ofthe first force is greater than a second threshold value. The processormay determine that the first robotic arm has collided with the objectbased on determining that the second component of the first force isgreater than the second threshold value, where the second thresholdvalue greater than an expected force of insertion of the steerableinstrument into the patient. In this embodiment, the second thresholdmay be selected to be greater than the expected force of insertion alongthe first axis, such that any component of the force measured in thefirst axis that is greater than the second threshold may be determinedto be due to a collision with an object.

In response to determining that the first and second forces are notindicative of a collision, the method 2000 may continue at block 2015,where the processor determines whether the first and second forces areindicative of misalignment. In certain implementations, the processormay determine that both of the first and second forces are greater thana third threshold force and determine that that the first and secondrobotic arms are misaligned in response to determining that both of thefirst and second forces are greater than the third threshold force.

The processor may also determine insertion data that indicates that thesecond medical instrument was being driven (e.g., inserted or retracted)through the first medical instrument at the time that the second forcewas detected. The insertion data may be stored in the memory and may bedetermined based on at least one of: the position of the first andsecond robotic arms and instructions to drive the second medicalinstrument received from a user. The processor may determine that thefirst and second robotic arms are misaligned in response to determiningthat the insertion data indicates that the second medical instrument wasbeing driven (e.g., inserted or retracted) through the first medicalinstrument. Further, in certain implementations, the processor maydetermine the forces experienced by the IDMs of the first and secondrobotic arms are not due to misalignment when the second medicalinstrument is not being driven through the first medical instrumentduring measurement of the first and second forces.

In another implementation, the insertion data may indicate that thefirst medical instrument was being driven at the time that the first andsecond torque values were measured. The processor may determine that thefirst force is greater than the threshold value and determine that thefirst robotic arm is misaligned with a patient introducer in response todetermining that the insertion data indicates that the first medicalinstrument was being driven and determining that the first force isgreater than the first threshold value. The patient introducer may be adevice configured to guide the first medical instrument into thepatient. In certain implementations, the system may be configured todetermine a force exerted on the patient introducer. In theseimplementations, the processor may determine whether the force appliedto the patient introducer and the first force are in opposing directionsand determine that the first IDM is misaligned with the patientintroducer in response to the force applied to the patient introducerand the first force being in opposing directions.

In some embodiments, the processor may be further configured todetermine that the first and second forces are in opposing directions.The processor may also determine that a difference between themagnitudes of the first and second forces is less than a thresholddifference. The processor may determine that the first and secondrobotic arms are misaligned in response to determining that the firstand second forces are in opposing directions and determining that thedifference between the magnitudes of the first and second forces is lessthan the threshold difference. That the first and second forces havingsimilar magnitudes in opposing directions may be indicative ofmisalignment since the second medical instrument is coupled to each ofthe first and second IDMs through the insertion of the second medicalinstrument into the working channel of the first medical instrument.

In response to determining that one of the first and second robotic armshave collided within an object (in block 2010) or determining that thefirst and second robotic arm are misaligned, at block 2020, theprocessor provides an indication of the collision or misalignment. Forexample, the processor may encode an indication of the collision ormisalignment and provide the encoded indication to a display configuredto render the encoded data. In certain implementations, the indicationmay not specify whether the event is a collision or a misalignment. Forexample, the indication may simply inform the user that acollision/misalignment error has been detected.

In other embodiments, the processor may encode information indicative ofthe type of event into the indication. For example, the indication mayspecify at least one of: whether a collision has occurred, which arm(s)are involved in the collision, whether a misalignment has occurred, andwhich arms are involved in the misalignment.

In response to determining that a collision or misalignment hasoccurred, the processor may prevent the user from further advancing thesteerable instrument into the patient. The indication may furtherprovide instructions to the user to retract the steerable instrumentfrom the patient and reset the system. The processor may also beconfigured to receive an input from the user indicating that the sourceof the collision or misalignment has been addressed. In response toreceiving an input that the collision or misalignment has been resolved,the processor may allow the user to continue the medical procedure. Themethod 2000 ends at block 2025.

F. Further Example Collision and Misalignment Technique.

In one example implementation, the surgical robotic system may beconfigured to detect a collision of a robotic arm. FIG. 21 is aflowchart illustrating an example method operable by a surgical roboticsystem, or component(s) thereof, for detecting a collision in accordancewith aspects of this disclosure. For example, the steps of method 2100illustrated in FIG. 21 may be performed by a processor of a surgicalrobotic system. For convenience, the method 2100 is described asperformed by the processor of the system.

The method 2100 begins at block 2101. At block 2105, the processormeasures a first torque value at a joint of a robotic arm based on anoutput of a torque sensor. The robotic arm may include: two linkagesconnected by the joint, a torque sensor configured to detect torquebetween the two linkages, and an instrument device manipulator (IDM)connected to a distal end of the robotic arm. At block 2110, theprocessor determines a second torque value at the joint based on aposition of the robotic arm. The second torque value may be indicativeof a gravitational component of the torque between the two linkages.

At block 2115, the processor determines a force at the IDM based adifference between the first and second torque values. At block 2120,the processor determines whether the robotic arm has collided with anobject based on the force at the IDM. In certain implementations, theprocessor may provide an indication that the robotic arm has collidedwith an object in response to determining that the robotic arm hascollided with the object. The method ends at block 2125.

3. Implementing Systems and Terminology.

Implementations disclosed herein provide systems, methods and apparatusfor detecting a collision or misalignment of one or more robotic arms ofa surgical robotic system. This detection may be based on, in certainembodiments, torque measurements performed at the joints of the roboticarm(s).

It should be noted that the terms “couple.” “coupling,” “coupled” orother variations of the word couple as used herein may indicate eitheran indirect connection or a direct connection. For example, if a firstcomponent is “coupled” to a second component, the first component may beeither indirectly connected to the second component via anothercomponent or directly connected to the second component.

The techniques for detection of collision and/or misalignment describedherein may be stored as one or more instructions on a processor-readableor computer-readable medium. The term “computer-readable medium” refersto any available medium that can be accessed by a computer or processor.By way of example, and not limitation, such a medium may comprise randomaccess memory (RAM), read-only memory (ROM), electrically erasableprogrammable read-only memory (EEPROM), flash memory, compact discread-only memory (CD-ROM) or other optical disk storage, magnetic diskstorage or other magnetic storage devices, or any other medium that canbe used to store desired program code in the form of instructions ordata structures and that can be accessed by a computer. It should benoted that a computer-readable medium may be tangible andnon-transitory. As used herein, the term “code” may refer to software,instructions, code or data that is/are executable by a computing deviceor processor.

The methods disclosed herein comprise one or more steps or actions forachieving the described method. The method steps and/or actions may beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isrequired for proper operation of the method that is being described, theorder and/or use of specific steps and/or actions may be modifiedwithout departing from the scope of the claims.

As used herein, the term “plurality” denotes two or more. For example, aplurality of components indicates two or more components. The term“determining” encompasses a wide variety of actions and, therefore,“determining” can include calculating, computing, processing, deriving,investigating, looking up (e.g., looking up in a table, a database oranother data structure), ascertaining and the like. Also, “determining”can include receiving (e.g., receiving information), accessing (e.g.,accessing data in a memory) and the like. Also, “determining” caninclude resolving, selecting, choosing, establishing and the like.

The phrase “based on” does not mean “based only on,” unless expresslyspecified otherwise. In other words, the phrase “based on” describesboth “based only on” and “based at least on.”

The previous description of the disclosed implementations is provided toenable any person skilled in the art to make or use the presentinvention. Various modifications to these implementations will bereadily apparent to those skilled in the art, and the generic principlesdefined herein may be applied to other implementations without departingfrom the scope of the invention. For example, it will be appreciatedthat one of ordinary skill in the art will be able to employ a numbercorresponding alternative and equivalent structural details, such asequivalent ways of fastening, mounting, coupling, or engaging toolcomponents, equivalent mechanisms for producing particular actuationmotions, and equivalent mechanisms for delivering electrical energy.Thus, the present invention is not intended to be limited to theimplementations shown herein but is to be accorded the widest scopeconsistent with the principles and novel features disclosed herein.

1-20. (canceled)
 21. A robotic system, comprising: a first roboticmanipulator comprising: at least one joint; and an instrument driverconfigured to drive a first medical instrument within a patient; one ormore processors; and data storage storing computer-executableinstructions configured to cause the one or more processors to:determine, based on at least one of position data or first torqueassociated with the first robotic manipulator, that the first medicalinstrument is misaligned with a second medical instrument.
 22. Therobotic system of claim 21, wherein: the position data indicatespositions of each of a plurality of linkages coupled to one or more ofthe at least one joint; and said determining that the first medicalinstrument is misaligned with the second medical instrument is based atleast in part the position data.
 23. The robotic system of claim 22,further comprising an encoder formed on one of the at least one joint,wherein the instructions are further configured to cause the one or moreprocessors to determine the position data based at least in part onfeedback from the encoder.
 24. The robotic system of claim 22, whereinthe instructions are further configured to cause the one or moreprocessors to cause a user notification of misalignment to be providedin response to said determining that the first robotic manipulator ismisaligned with the second medical instrument.
 25. The robotic system ofclaim 21, wherein: the first torque is experienced while the instrumentdriver of the first robotic manipulator is being advanced along a firstaxis; the instructions are further configured to cause the one or moreprocessors to determine that at least a portion of the first torque isin a plane perpendicular to the first axis; and said determining thatthe first medical instrument is misaligned with the second medicalinstrument is based at least in part on said determination that the atleast a portion of the first torque is in the plane perpendicular to thefirst axis.
 26. The robotic system of claim 21, further comprising asecond robotic manipulator comprising: at least one joint; and aninstrument driver configured to drive a second medical instrument. 27.The robotic system of claim 26, wherein: the instructions are furtherconfigured to cause the one or more processors to: determine a secondtorque associated with the second robotic manipulator; and determinethat at least one of the first torque or the second torque is greaterthan a threshold; and said determining that the first medical instrumentis misaligned with the second medical instrument is based at least inpart on said determination that at least one of the first torque or thesecond torque is greater than the threshold.
 28. A robotic system,comprising: a first robotic manipulator, comprising: at least one joint;an instrument driver configured to drive a first medical instrumentwithin a patient; and torque sensing means configured to generatesignals indicative of a first force experienced by the at least onejoint of the first robotic manipulator when the instrument driver of thefirst robotic manipulator is advanced along a first axis; one or moreprocessors; and data storage storing computer-executable instructionsconfigured to cause the one or more processors to: determine that thefirst medical instrument is misaligned with a second medical instrumentbased at least in part on the first force.
 29. The robotic system ofclaim 28, wherein the torque sensing means comprises one or more torquesensors associated with one or more of the at least one joint.
 30. Therobotic system of claim 28, wherein the instructions are furtherconfigured to cause the one or more processors to: determine a secondforce experienced by a second robotic manipulator including aninstrument driver configured to drive the second medical instrument. 31.The robotic system of claim 30, wherein the instructions are furtherconfigured to cause the one or more processors to: determine an adjustedfirst force by removing a first component of the first force that is dueto gravity; and determine an adjusted second force by removing a secondcomponent of the second force that is due to gravity; wherein saiddetermination that the first medical instrument is misaligned with thesecond medical instrument is based at least in part on the adjustedfirst force and the adjusted second force.
 32. The robotic system ofclaim 30, wherein the instructions are further configured to cause theone or more processors to: determine that the first and second forcesare not indicative of a collision; and determine that both the first andsecond forces are greater than a first threshold; wherein saiddetermining that the first medical instrument is misaligned with thesecond medical instrument is at least partially in response to saiddetermining that the first and second forces are greater than the firstthreshold.
 33. The robotic system of claim 32, wherein said determiningthat the first and second forces are not indicative of a collisioninvolves determining that at least one of the first force or the secondforce is less than a second threshold.
 34. The robotic system of claim28, wherein the instructions are further configured to cause the one ormore processors to determine a first component of the first force alonga second axis that is perpendicular to the first axis.
 35. The roboticsystem of claim 34, wherein: the instructions are further configured tocause the one or more processors to determine that the first componentof the first force is greater than a first threshold value; and saiddetermining that the first medical instrument is misaligned with thesecond medical instrument is based at least in part on saiddetermination that the first component of the first force is greaterthan the first threshold value.
 36. A robotic system, comprising: afirst robotic manipulator, comprising: at least one joint; one or moretorque sensors; and an instrument driver configured to drive a firstmedical instrument within a patient; one or more processors; and datastorage storing computer-executable instructions configured to cause theone or more processors to: measure a first torque value at the at leastone joint based at least in part on output from the one or more torquesensors; determine a second torque value indicative of a gravitationalcomponent of the first torque value; and determine a gravity-compensatedtorque value based at least in part on the first torque value and thesecond torque value.
 37. The robotic system of claim 36, wherein thegravity-compensated torque value is based on a difference between thefirst torque value and the second torque value.
 38. The robotic systemof claim 36, wherein said determining the second torque value is basedat least in part on a position of the first robotic manipulator.
 39. Therobotic system of claim 38, wherein said determining the second torquevalue involves determining at least one of: a position of two linkagesconnected by the at least one joint; or an angle formed between the twolinkages.
 40. The robotic system of claim 36, wherein the instructionsare further configured to cause the one or more processors to detect,based at least in part on the gravity-compensated torque value, at leastone of: a collision between the first robotic manipulator and anotherobject; or a misalignment of the first medical instrument with anotherinstrument.